1. Field of the Invention
The present invention relates generally to the selective harvesting of raspberry, blackberry, and other species and hybrids in the Rubus genus, as well as strawberry and other species and hybrids in the Fragaria genus. More specifically, the present invention relates to a method and apparatus for removing unwanted plants, or unwanted portions of plants, from a plant bed to facilitate more effective harvesting of the desired plants or portions of plants. While the present invention has application to other species and hybrids in the Rubus and Fragaria genera, because of the broad application to raspberries and strawberries in particular, application of the present device and method to those plants in particular will be detailed.
2. Background
Raspberry cultivars readily produce new shoots from the roots of the plant. In a planting process called “suckering,” new nursery plantings are established by taking advantage of the plant's ability to produce these suckers. Commercial nurseries grow plants and harvest roots to supply the plantable rootstocks to fruit growers. As the plants destined for rootstock go dormant in the fall, they are harvested. Prior to the root harvesting process, the dormant plants are mowed down to a height that leaves only a short length of cane protruding from the surface of the planted bed of soil. This short length of cane and the associated woody portion of plant material that forms the transition from cane to roots, the “crown,” is left in the bed and is currently harvested along with the roots. Current practice requires that these crowns be removed as a secondary operation in the packing shed. The crown removal process is currently performed manually. This is a time-consuming and expensive process. The present invention eliminates this secondary operation by removing the crowns from the planted bed before the roots are harvested.
Strawberry plant-stocks are grown in a different fashion. “Mother” plants are planted in rows. The mother plants produce multiple stolons called runners. These horizontal runners are sent outward from the base of the strawberry plants. At variable distances, new strawberry plants (daughter plants) form at the runner nodes. This is possible due to the strawberry plant's ability to form adventitious specialized roots at the nodes along a runner. Wherever these roots touch nutritious soil, they will continue to grow into that soil and establish a new clonal plant or daughter plant that is genetically identical to the mother plant that originally formed the runners. These vegetatively propagated plants are later harvested to be sold to commercial growers producing fruit for consumption.
As with raspberries, strawberries share the common problem of relying on harvesting systems that harvest all the plant material, including the undesirable mother plant. Currently, standard practice is to remove these mother plants as a secondary operation during the cleaning, grading, and packaging process prior to putting plants into cold storage. This is an expensive process that is currently done by hand. Attempts to automate mother plant removal in the packing shed through the use of technologically advanced sorting systems have proven unsuccessful.
The present invention eliminates the secondary separation operation described above by mechanically removing unwanted mother plants or portions of mother plants, in situ, before the harvesting operation.